AppFrame.java

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;

public class AppFrame extends JFrame {
    private TitleBar titleBar;
    private List list;
    private JScrollPane listScrollPane;
    private ButtonPanel btnPanel;

    public AppFrame() {
        this.setSize(800, 600);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setLayout(new BorderLayout());

        titleBar = new TitleBar();
        list = new List();
        btnPanel = new ButtonPanel();

        // Wrap list inside a JScrollPane for scrolling support
        listScrollPane = new JScrollPane(list);
        listScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

        this.add(titleBar, BorderLayout.NORTH);
        this.add(listScrollPane, BorderLayout.CENTER);
        this.add(btnPanel, BorderLayout.SOUTH);

        addListeners();

        this.setVisible(true);
    }

    private void addListeners() {
        btnPanel.getAddTask().addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                String taskName = JOptionPane.showInputDialog(null, "Enter task name:");
                if (taskName != null && !taskName.trim().isEmpty()) {
                    Task task = new Task(taskName);
                    list.add(task);
                    list.updateNumbers();

                    task.getDone().addActionListener(new ActionListener() {
                        @Override
                        public void actionPerformed(ActionEvent e) {
                            task.changeState();
                            list.updateNumbers();
                        }
                    });

                    listScrollPane.revalidate();  // Refresh layout after adding task
                    listScrollPane.repaint();
                }
            }
        });

        btnPanel.getClear().addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                // Loop backwards to safely remove components while iterating
                for (int i = list.getComponentCount() - 1; i >= 0; i--) {
                    if (list.getComponent(i) instanceof Task) {
                        Task task = (Task) list.getComponent(i);
                        // You will need a getter in Task class for checked status
                        if (task.isChecked()) { 
                            list.remove(i);
                        }
                    }
                }
                list.updateNumbers();
                list.revalidate();
                list.repaint();
            }
        });
    }
}